Water sorption and transport in Silurian shales

We have studied the transport of water in shales through gravimetric water vapour sorption experiments. Kinetic data have been evaluated and several kinetic models have been compared, with emphasis on time-dependent diffusivity models. The effective diffusivities as a function of relative pressure show an initial increase corresponding to the sorption to primary adsorption centres, followed by water cluster formation. The final decrease in effective diffusivity is connected with flattening of the pore-mouth meniscus. Introducing the flow rate kinetic parameter enables samples with different amounts of adsorbed water to be compared, showing that the highest value of the flow rate kinetic parameter is connected with the sample with largest surface area and the greatest micropore volume.